Structural Behavior of Hybrid Fiber Reinforced

Concrete Elements M.Sasi Kumar

1, M.Kanitha

2

1, 2 Assistant Professor, Department of Civil Engineering, M.Kumarasamy College of Engineering, Karur.

E-mail: sasi.mj@gmail.com

Abstract— This paper labels the study of hybrid fiber reinforced concrete specimen’s structural behavior elements. Fibers

influenced on the hybrid reinforced specimens structural characteristics are analyzed. Samples having various fiber-volume

fractions will be explored. Structural characteristics investigates test like compressive strength, flexural strength and tensile

strength. The incorporation of Steel and Polyester (Recron 3S) fiber varies from range 0.1 to 1% volume fraction. From the

results obtained the concrete specimens made with 0.5 % possess high structural behavior compared to other specimens made.

The results attained is also equated with the predictable specimens of beam and beam-column joint.

Index Terms— Beam-column joints, Hybrid fiber reinforced, Polyester, Recron 3S

—————————— ——————————

1 INTRODUCTION

Concrete is generally delivered and widely used than all other as a construction material,. Concrete strength varies with the preparations and the incorporations of the material involved in the manufacturing, like Plain concrete possesses a very less tensile strength and little resistance to cracking [1,2]. In addition with these the microstructural study like internal micro cracks are characteristically present in the concrete if the concrete possess low strength and improper arrangements. Such micro cracks lead to the propagation of poor tensile strength which, in the long run leading to fragile fracture of the concrete. The mandatory reason for incorporating the fibers include it reduces the air voids reasonably, in addition with the reduction of water voids. Creep resistance can be attained with the incorporation of graphite and glass fibers. [3,4,5].

Modulus of elasticity of fiber plays a major role in

fiber reinforced concrete for efficient stress transfer. Fibers like steel, carbon and glass gives high modulus and stiffness. This the major reason for selecting the Steel fiber in this project. The sequential factor also plays vital role in incorporating the fiber is volume of fibers. The higher addition more than the optimum would result in segregation and harshness in the concrete specimens. [6, 7]. Aspect ratio of fibers remains the constant reason for the selection of quantity of fibers, where it differs based on the properties and nature of concrete. The optimum aspect ratio is 75 where it exceeds the concrete attains certain less toughness and strength.

Orientation of fibers plays some roles in the toughness and strength attained in FRC. From the study the fibers arranged parallel to the applied load attains quite high results when compared to orientations done random and perpendicular to the load. The orientation continued with the size and shape of the fiber imply in the applications like steel fibers round in shape available as reinforcement.

Thus from the above conditions the steel fiber proposed to use is crimped round steel fiber and is purchased from Bakul castings. The Recron 3S fibers are purchased from Reliance Regional Office in Bangalore.

Besides, steel reinforcement is espoused to overcome high theoretically tensile stresses and shear stresses at critical location in concrete member. When the root analysis of this most cases induce that micro cracks development should be suppressed with the method of additional of additives or filler materials which significantly increase the strength of concrete, which in turn produce concrete with homogenous tensile properties [9]. The expansion of strands was gotten as an answer for create concrete in perspective on expanding its elastic and flexural quality, custom of fastener that could join Portland concrete in the holding with concrete frameworks. [13, 14, 15]. 'Fiber strengthened cement' (FRC) is made up with concrete, different sizes of aggregate, which coordinate with discrete, irregular filaments. Filaments are most regularly spasmodic, arbitrarily dispersed all through the concretes frameworks. [16,17]

2 Materials and Methods

2.1 Cement

OPC 53 grade was adapted to the concrete cube making process. The properties of Cement like consistency, Initial setting time, last setting time and fineness modulus are tried for the examples and the outcomes are given beneath.

TABLE 1- PROPERTIES OF CEMENT

2.2 Fine aggregate

The river sand available in the nearby area was taken for casting the test specimens. The properties of river sand are studies with the reference of BIS 2386-1963, the obtained results are shown below in table .

Properties Obtained value

Specific gravity 3.15 Consistency 30.5% Finess 2.0% Initial setting time 95 min Final setting time 600 min

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TABLE 2 - FINE AGGREGATE -PHYSICAL PROPERTIES

2.3 Coarse aggregate

The test results of coarse aggregate shown in Table 3. Specific gravity and water absorption are conducted based on codal provision.

TABLE 3 - PROPERTIES OF COARSE AGGREGATE

3 STRUCTURAL PROPERTIES UNDER STATIC LOADING

The Reinforced cement concrete beam of 2m length is provided with two numbers of 8mm diameter bars in the tensile zone and 2 numbers of 8mm diameters bars in the compressive zone, 6mm diameter bars for shear reinforcement at 100mm spacing as per arrangements given in Fig 1. The conventional and fiber reinforced concrete beams were tested under middle third loading. At every 5 kN interval, the deflection values were measured using dial gauges. Initial cracking load was noted by carefully watching the tested beam. For this purpose at one of the bottom reinforcements electrical strain gauges of 200 mm gauge length were pasted before casting. The next important points of ultimate and failure loads were noted. The corresponding deflection values were also measured.

FIG.1 REINFORCEMENT DETAILS OF BEAM

4 RESULTS AND DISCUSSION

1. The mechanical properties possess enhanced strength results

with 0.5% hybrid fiber reinforced concrete compared to other volume of fractions. The results incorporated in percentage were found that the 0.5% hybrid fiber reinforced concrete is 23% and 54% higher in strength more than the conventional concrete (Fig.2, 4).

2. The split rigidity accomplished shows the 0.5% and 1% recron fiber fortified concrete was seen as generally more than the 0.5% half and half fiber strengthened concrete. It was discovered that the 0.5% hybrid fiber fortified concrete is 14.7% more than the regular concrete, however the split elasticity of 0.5% half breed fiber strengthened concrete is efficient. (Fig.3).

3. Added with the advantage of the 0.5% hybrid fiber reinforced concrete ,the young’s modulus of the 0.5% hybrid fiber reinforced concrete was found to be relatively more than all the volume fractions. It was found that the is 12.5% more than the conventional concrete (Fig.5).

4. Form the above discussions we can conclude reasonably that the 0.5% hybrid fiber reinforced concrete found be ideal fiber content , the graphical representation was given in (Fig.6,7,8).

5. Conventional beam specimen carried maximum load of 80 kN and the 0.5% hybrid fibre reinforced concrete beam specimen carried a maximum load of 85 KN. The percentage reduction in deflection is 5% when compared to the conventional concrete specimen (Fig.9,10,11).

6. The ductility factor, energy absorption capacity and the toughness of the 0.5% HFRC beam is 8%, 3% and 4% more than the conventional concrete specimen (Fig.12).

7. Beam – Column joint with 0.5% HFRC showed an increased load carrying capacity of about 14.28 %. The percentage reduction in deflection is 35.03% when compared to the conventional concrete specimen (Fig.13)

TABLE 3 – COMPRESSION AND TENSILE STRENGTH

S. No. Sand Type Properties Zone

1. River Sand Specific gravity 2.63

2. River sand Water absorption 1.0%

S. No. Properties Values Customary values

1. Specific gravity 2.79 2.5 – 2.7

2. Water absorption 0.5% 0.1 – 2 %

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COMPARISON OF DIFFERENT PROPORTION OF CONCRETE

S. No.

Specimens

Compressive strength

Split tensile strength

7 Days 28

Days 7 Days

28 Days

1 Conventional

Concrete 14.9 29.02 1.43 2.5

2 0.5% RFRC 26.44 32.47 2.08 2.98

3 1% RFRC 29.92 32.6 2.43 3

4 0.5% SFRC 29.93 32.61 2.52 2.51

5 1% SFRC 22.32 29.53 2.05 2.71

6 0.5% HFRC 34.65 37.78 2.43 2.81

7 1% HFRC 35.15 30.67 2.51 2.43

TABLE 4 – FLEXURAL STRENGTH AND ELASTIC

MODULUS COMPARISON OF DIFFERENT PROPORTION OF CONCRETE

S. No.

Specimens Flexural Strength

Elastic Modulus of concrete

28 Days 28 Days

1 Conventional

Concrete 3.25 2.37 x 104

2 0.5% RFRC 6.67 2.45 x 104

3 1% RFRC 6.27 2.60 x 104

4 0.5% SFRC 6.92 2.47 x 104

5 1% SFRC 5.88 2.54 x 104

6 0.5% HFRC 7.06 2.71 x 104

7 1% HFRC 5.49 2.57 x 104

Fig.2 COMPARISON OF COMPRESSIVE STRENGTH OF CONCRETE

SPECIMENS

Fig.3 COMPARISON OF SPLIT TENSILE STRENGTH OF CONCRETE

SPECIMENS

Fig.4 COMPARISON OF FLEXURAL STRENGTH OF CONCRETE

SPECIMENS

Figure.5 COMPARISON OF ELASTIC MODULUS OF CONCRETE

SPECIMENS

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Fig.6 LOAD- DEFLECTION CURVE FOR CONVENTIONAL CONCRETE

Fig.7 LOAD- DEFLECTION CURVE FOR 0.5% RFRC

Fig.8 LOAD- DEFLECTION CURVE FOR 1% RFRC

Fig.9 LOAD- DEFLECTION CURVE FOR 0.5% SFRC

Fig.10. LOAD- DEFLECTION CURVE FOR 1% SFRC

Fig.11 LOAD- DEFLECTION CURVE FOR 0.5% HFRC

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Fig.12 LOAD- DEFLECTION CURVE FOR 1%HFRC

Fig.13 LOAD- DEFLECTION CURVE FOR CONVENTIONAL BEAM-

COLUMN JOINT

4 CONCLUSION

Hence the mechanical properties compressive quality, flexural quality and versatile modulus of 0.5% Hybrid Fiber Reinforced Concrete is advantageous. The fiber volume fraction is augmented to 0.5% HFRC. The structural behavior of conventional beam and beam column joint is compared with that of 0.5% HFRC specimens. The 0.5% HFRC beam and beam column joint carries maximum load and shows reduction in deflection.

References [1] Banthia, N., & Nandakumar, N. (2003). Crack growth

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[2] Chen, B., & Liu, J. (2004). Residual strength of hybrid-fiber-reinforced high-strength concrete after exposure to high temperatures. Cement and Concrete Research, 34(6), 1065-1069.

[3] Qian, C., & Stroeven, P. (2000). Fracture properties of concrete reinforced with steel–polypropylene hybrid fibres. Cement and Concrete Composites, 22(5), 343-351.

[4] Sugama, T., & Pyatina, T. (2014). Toughness Improvement of Geothermal Well Cement at up to 300 C: Using Carbon Microfiber. Open Journal of Composite Materials, 4(04), 177.

[5] Lee, C., & Kim, H. (2010). Orientation factor and number of fibers at failure plane in ring-type steel fiber reinforced concrete. Cement and Concrete Research, 40(5), 810-819..

[6] de Carvalho, M. R. P., Fairbairn, E. D. M. R., Toledo Filho, R. D., Cordeiro, G. C., & Hasparyk, N. P. (2010). Influence of steel fibers on the development of alkali-aggregate reaction. Cement and Concrete Research, 40(4), 598-604.

[7] Sivakumar, A., & Santhanam, M. (2007). A quantitative study on the plastic shrinkage cracking in high strength hybrid fibre reinforced concrete. Cement and concrete composites, 29(7), 575-581.

[8] Sun, W., Chen, H., Luo, X., & Qian, H. (2001). The effect of hybrid fibers and expansive agent on the shrinkage and permeability of high-performance concrete. Cement and concrete research, 31(4), 595-601.

[9] Yao, W., Li, J., & Wu, K. (2003). Mechanical properties of hybrid fiber-reinforced concrete at low fiber volume fraction. Cement and concrete research, 33(1), 27-30.

[10] Qian, C. X., & Stroeven, P. (2000). Development of hybrid polypropylene-steel fibre-reinforced concrete. Cement and Concrete Research, 30(1), 63-69.

[11] Balaji, G., & Vetturayasudharsanan, R. (2019). Experimental investigation on flexural behaviour of RC hollow beams. Materials Today: Proceedings.

[12] Dineshkumar, R., & Ramkumar, S. (2019). Review paper on fatigue behavior of reinforced concrete beams. Materials Today: Proceedings.

[13] Ramkumar, S., & Dineshkumar, R. (2019). Experimental study on impact on fineness of sand and M-sand in M20 grade of concrete. Materials Today: Proceedings.

[14] Hemavathi, S., Kumaran, A. S., & Sindhu, R. (2019). An experimental investigation on properties of concrete by using silica fume and glass fibre as admixture. Materials Today: Proceedings.

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